If you have ever been on a tropical island, you may have experienced that as the sun rises, the temperature shoots up, only to start falling a few hours later due to the formation of clouds. Then, after increasing again for a few hours, the temperature peaks in the early afternoon, followed by cooling rain. It happens every day all over the tropics, but the climate models do a lousy job in reproducing this weather pattern. Thereby they miss out on what may be the most potent natural cooling mechanism on earth.
The Iris Effect
One of the first serious attempts to understand cooling mechanisms in the tropics was Dr. Richard Lindzen’s proposed “iris effect” in 2001. He and his colleagues presented evidence that elevated sea surface temperatures caused fewer cirrus clouds, leading to heat radiation leaking out into space, thereby cooling the planet.
Those who believe some great climate catastrophe is on the way quickly labeled this “debunked,” but over the years, more papers supporting the theory have emerged. In 2007, Dr. Roy Spencer found that his satellite data agreed with the iris effect. Two other scientific articles appeared in 2015 and 2017 to support the hypothesis.
The Thunderstorm Thermostat
Independent scientist and longtime resident in the tropics, Willis Eschenbach, has a different take on the same phenomenon. His starting point was that the climate is amazingly stable. How can it be that such a chaotic and dynamic system could vary by only ±0.3°C over a century? He found the short answer to be the oceans, especially the thunderstorm cycle in the tropics.
He noted a strong correlation between warm tropical days and cooling in the days that followed, which can be explained almost entirely by thunderstorms that block the sun, dry the atmosphere, and allow radiation to escape. The crux of the phenomenon is that below a sea surface temperature of 26°C, practically no thunderstorms form. Once the temperature hits this threshold, clouds rapidly gather and aggregate into rain-heavy mega-clouds that quickly cool a region with showers.
Eschenbach’s point is that the ocean is a temperature-triggered cloud-generating machine, and the climate models are largely blind to it.
Another giant clue indicates that something is cooling the tropics. The climate models predict that there should be a strong warming signal in the tropical troposphere, far up above the clouds. The reason is that warming should lead to more water vapor reaching higher up into the atmosphere, and since it is the strongest of all greenhouse gases, it should be warming like crazy there.
But it’s not. There is no discernible warming at all, which indicates that something is drying the atmosphere, and it must be a mechanism so powerful that it cancels the entire manmade greenhouse effect in that area.
From this, we can conclude that the models have a long way to go before they can predict the climate.